The present disclosure relates to a method for producing an acid gas separation composite membrane, and an acid gas separation membrane module, in which an acid gas in a gas to be separated is selectively separated using a facilitated transport membrane.
In recent years, development has advanced in techniques for selectively separating an acid gas such as CO2 in a gas to be separated. For example, the development has been made on a module for gas separation for separating a CO2 gas from the gas to be separated by a CO2 gas separation membrane through which the CO2 gas is selectively transmitted.
Gas separation membranes are generally classified into a facilitated transport membrane and a dissolution diffusion membrane. The facilitated transport membrane contains inside a membrane a substance (carrier) that selectively and reversibly reacts with one or a plurality of specific components inside the gas to be separated, and utilizes the carrier to transport the specific components on a side opposite to the membrane to cause separation. Moreover, the dissolution diffusion membrane utilizes differences in solubility in the membrane and diffusivity inside the membrane between the acid gas and a separation target substance.
The facilitated transport membrane utilizes transport based on a selective reaction between the specific component and the carrier. Thus, separation with high selectivity can be made, and a transmission rate of a separated gas inside the membrane is also high. Accordingly, the module for gas separation (facilitated transport type module for gas separation) in which the facilitated transport membrane is used has excellent separation characteristics, and has attracted attention.
In general, the facilitated transport type module for gas separation is provided with a member for fed gas flow channel serving as a flow channel of the gas to be separated to be fed, a gas separation member (gas separation composite membrane) in which the facilitated transport membrane is retained on a porous support, and a member for transmitted gas flow channel serving as a flow channel of a transmitted gas that is transmitted through the facilitated transport membrane, and separated.
In the gas separation composite membrane that plays a role of separation performance in the module for gas separation, high separation performance and high durability, and also production adaptability thereof are required. As the facilitated transport membrane having high carrier retention or a production method therefor, a facilitated transport membrane in which the membrane is formed by impregnating a carrier into a porous polymer membrane or a hydrogel membrane is disclosed (see Patent Documents 1 to 3).
Japanese Unexamined Patent Publication No. 7(1995)-060078 (hereinafter, Patent Document 1) discloses a method for producing a facilitated transport membrane that has excellent carbon dioxide separation performance and also excellent retention of a carbon dioxide carrier liquid, and even if the membrane is brought into contact with water, causes no easy reduction of membrane performance, in which a hydrophilic vinyl monomer vapor is brought into contact onto a support having a porous polymer membrane subjected to plasma treatment to form a hydrophilic polymer membrane thereon, and then the carbon dioxide carrier liquid is impregnated and retained thereinto through the hydrophilic polymer membrane.
Japanese Patent Publication No. 7(1995)-102310 (hereinafter, Patent Document 2) discloses a carbon dioxide separation device provided with a facilitated transport membrane that is formed by using as a support a hydrophilic porous membrane, and casting a copolymer gel containing a carbon dioxide carrier thereon. The Document describes that the hydrophilic porous membrane is used as the support to facilitate membrane formation and to fill pores of the porous membrane also with the copolymer gel, and therefore a carbon dioxide separation membrane having only a limited number of defects can be obtained.
Japanese Unexamined Patent Publication No. 2009-195900 (hereinafter, Patent Document 3) describes that an uncrosslinked copolymer liquid is coated onto a support, and then crosslinked to cause insolubilization in water, and then a carbon dioxide carrier aqueous solution is absorbed thereinto to allow production of a carbon dioxide separation membrane having excellent long-term stability and high shape retention.